The Competition and Markets Authority (CMA) said on Wednesday it believed that in over 350 local areas where there is currently an overlap between Tesco shops and Booker-supplied independent grocery retailers, or ‘symbol’ stores, shoppers could face worse terms when buying their groceries.

It said there were concerns that if the deal was cleared there was potential for Booker to reduce the wholesale services or terms it offers the ‘symbol’ stores it currently supplies, in order to drive customers to their local Tesco.

The CMA said other concerns were raised and considered in the phase 1 probe, opened in May, but it had not found it necessary to conclude on all of these given the referral.

The CMA’s in-depth phase 2 investigation lasts 24 weeks, which means its final report will be published before Christmas. ($1 = 0.7797 pounds) (Reporting by James Davey; editing by Kate Holton)